Cosmonaut Keep is the first book of the Engines of Light trilogy by Ken MacLeod, combining space opera with a unique take on the ufo mythos and a variety of leftist and libertarian political perspectives. It is told in two widely different alternating timelines, both focusing on the dream of interstellar travel.
The first timeline is set in a near-future Edinburgh, in a world where a neo–Soviet Russia has beaten back the United States and installed a kinder, gentler socialism in Europe. Matt Cairns is a computer programmer, and a member of the International Workers of the World Wide Web (or Webblies). He stumbles upon a group of American libertarians trying to overthrow the Party for fun and profit, and ends up carrying a mysterious data disk containing what appear to be plans for light-speed travel and an antigravity spaceship. Meanwhile, a rebellious European space station claims to have made first contact with aliens within an asteroid.
The second timeline is set on Mingulay, a planet in the Second Sphere, an ancient multispecies civilization. The two oldest species are the krakens and the saurs, both millions of years old. The krakens (bioluminescent and intelligent giant squid) navigate the lightspeed starships that ply the Second Sphere, while the saurs (secretive beings descended from bipedal dinosaurs who look suspiciously like the Greys of ufology) pilot gravity skiffs (read: flying saucers). In addition to two other species of hominid, there are also humans descended from those abducted from Earth by the saurs and taken to the Second Sphere over the millenia. Above all are the gods, superintelligent communities of extremophile bacteria who live in comets and asteroids, whose one and only commandment is “Leave us alone!” In this timeline, we follow Gregor Cairns — a member of the Cosmonaut Families, the descendents of the crew of a human-piloted starship from Earth — whose family has been working secretly on an interstellar navigation problem for two hundred years.